The Local Buckling Strength of Partially Stiffened Type 3CR12 Stainless Steel Compression Elements in Beam Flanges

In this study the effect of the non-linear behaviour of stainless steels on the local buckling strength of partially stiffened compression elements in beam flanges is studied. The steel under investigation is Type 3CR12 stainless steel. Lipped channels were placed back to back to form a doubly symmetric lipped I-section. The different pIasticity reduction factors suggested in the ASCE3 and South African13 stainless steel design specification for stiffened and unstiffened compression elements are used to compare experimental results with theoretical predictions. It is concluded that the ASCE3 and South African13 stainless steel design specifications overestimate the local buckling stress in the beam flanges as well as the ultimate strength of partially stiffened stainless steel beams. The experimental results compare well with the theoretical predictions when the two plasticity reduction factors are used

The ring-opening polymerization of D,L-lactide in the melt initiated with tetraphenyltin

Melt polymerization conditions for D,L-lactide initiated with tetraphenyltin were studied with regard to polymer molecular weight and weight distributions. "Single" polymerization, "multiple"polymerization (four or eight reactions at the same time), and time-dependent studies are described. Single polymerizations using constant initiator concentrations resulted in a broad scattering of nonreproducible molecular weight values. Multiple polymerizations at constant initiator concentrations, however, resulted in nearly identical molecular weight profiles. Multiple polymerizations at different initiator concentrations did not show an inverse dependency of initiator concentration on polymer molecular weight. Both the single and multiple melt polymerizations resulted in rather broad molecular weight distributions. The presence of hydrolysis products of lactide during the melt polymerization most likely has a detrimental effect on molecular weight. After a short induction period the rather slow polymerization of D,L-lactide resulted in a maximal molecular weight followed by a slight decrease in molecular weight to a constant value. It is concluded that the polymerization of D,L-lactide in the melt initiated with tetraphenyltin does not proceed through a "living" mechanism

Warehouse design and planning: A mathematical programming approach

The dynamic nature of today's competitive markets compels organizations to an incessant reassessment in an effort to respond to continuous challenges. Therefore, warehouses as an important link in most supply chains, must be continually re-evaluated to ensure that they are consistent with both market's demands and management's strategies. A number of warehouse decision support models have been proposed in the literature but considerable difficulties in applying these models still remain, due to the large amount of information to be processed and to the large number of possible alternatives. In this paper we discuss a mathematical programming model aiming to support some warehouse management and inventory decisions. In particular a large mixed-integer nonlinear programming model (MINLP) is presented to capture the trade-offs among the different inventory and warehouse costs in order to achieve global optimal design satisfying throughput requirements.(undefined)info:eu-repo/semantics/publishedVersio

The Strength of Partially Stiffened Stainless Steel Compression Members

In this study the effect of the non-linear behaviour of stainless steels on the local buckling strength of partially stiffened compression elements is studied. The steel under investigation is a Type 304 stainless steel. Doubly symmetric hat section columns were manufactured by a press braking process and tested as stub columns to exclude overall buckling interaction. The different plasticity reduction factors\u27 suggested in the ASCE stainless steel design specification for stiffened and unstiffened compression elements are used to compare experimental results with theoretical predictions. It is concluded that the ASCE and South African stainless steel design specifications overestimate the local buckling stress as well as the ultimate strength of partially stiffened stainless steel compression elements. The experimental results compare well with the theoretical predictions when the two plasticity reduction factors are used

The Lateral Torsional Buckling Strength of Cold-formed Stainless Steel Beams

The findings of an investigation of the lateral torsional buckling strength of cold-formed stainless steel beams are reported in this study. The sections under consideration are cold-formed lipped channel sections spot-welded back to back to form doubly-symmetric lipped I-beams. The beams were fabricated from a modified AISI Type 409 stainless steel, designated Type 3CR12 corrosion resisting steel. The purpose of this study is to compare the experimental lateral torsional buckling strengths of doubly-symmetric beams to the theoretical predictions proposed by the ASCE Specification for the Design of Cold-Formed Stainless Steel Structural Members. It was concluded in this investigation that an acceptable prediction of beam strength may be obtained through the use of the tangent modulus approach adopted in the ASCE stainless steel design specification

The Strength of Partially Stiffened Stainless Steel Compression Members

The instability of partially stiffened stainless steel compression members due to local buckling of the flange element or flange and lip interaction has not been studied before. In this investigation the critical local buckling and post-buckling behaviour of cold-formed partially stiffened stainless steel compression elements is studied. It is concluded in this investigation that a plasticity reduction factor should be used to evaluate the critical local buckling stress as well as the effective width to calculate the ultimate capacity of partially stiffened stainless steel compression members

Prediction of Corner Mechanical Properties for Stainless Steels Due to Cold Forming

The results of a study of the degree of workhardening on stainless steel Types 304, 409, 430 and Type 3CR12 corrosion resisting steel due to cold work of forming are presented in this paper. Analytical inelastic stress-strain relationships are established for virgin tensile specimens. An equation for predicting the yield strength of comers are developed

Web Crippling of Stainless Steel Cold-formed Beams

The results of an investigation on the web crippling strength of cold-formed stainless steel channel sections are presented in this paper. The steels under consideration are AlSI Type 430 stainless steel and a modified AlSI Type 409, designated Type 3CR12 corrosion resisting steel. The lipped channel sections were manufactured by a press braking process. Beams were tested in pairs, lips facing, in an interior-one-flange loading configuration. Experimental results were compared with the theoretical predictions given in the 1991 edition of the Specification for the Design of Cold-Formed Stainless Steel Structural Members. It was concluded in this study that the experimental results compare reasonably well with the theoretical predictions. For longer bearing lengths the theoretical strengths appear to be conservative

Burst Strength of Type 304L Stainless Steel Tubes Subjected to Internal Pressure and External Forces

The findings of an investigation concerning the burst strength of cold-formed Type 304L stainless steel tubes subjected to internal pressure and static external forces are reported in this study. The use of cold-formed stainless steel longitudinally welded tube in pressurised processes in industry are limited due to the belief that seamless tubes have superior resistance to internal pressure. The primary objective of this study was to experimentally and theoretically describe the failure criteria for thin-walled longitudinally welded Type 304L stainless steel tubes subjected to internal pressure and static external point loads and torsion loads. Due to the diversity of the pipe manufacturing process, problem areas which were most likely to cause failures were identified. A microscopic study was done of the weld region where failure was expected in order to support the test results. It was found that cold-formed longitudinally welded Type 304L stainless steel tubes could attain very high bursting pressure values and could compete with seamless tubes in this respect. It was also found that the internal pressure was the most important criteria in tube failure and that the effect of static external forces could be neglected to a certain extent